You will need to use use either vapor deposition or sputtering to get a very thing but uniform coating of metal (or some conductive material) onto the glass However, most metals are reflective and how much you deposit will make the glass into more of a half-mirror type thing. Look at "Applied Science" youtube channel, he has lots of great videos of his experiences and projects in his amazing lab! In the video below, he is using a sputtering process to deposit a clear conductive coating of Indium Tin Oxide (ITO) onto a glass microscope slide. ITO, like steve pointed out, is a material which is commonly used for this reason. It is found in LCDs. He made this video as part of an project to make a homemade LCD!